1. Field of the Invention
The present invention relates to a touch system and a method thereof. More particularly, the present invention relates to an optical touch system supporting multi-touch and a touch object separating method thereof.
2. Description of Related Art
Along with the spread of Windows 7 operating system, all-in-one PC (AIO PC) with multi-touch function has gradually become the mainstream product in the market. Capacitive touch monitor offers the best touch control effect among all existing resistive, capacitive, and rear projection touch monitors. However, the cost of capacitive touch monitor is the highest and is increased along with the increase of screen size, which renders the usage benefit of the capacitive touch monitor become less economical.
In order to find a substitution for the capacitive touch monitor, an optical touch monitor which uses a light-sensitive device or an optical lens to detect a touch position is provided. Such optical touch monitor offers low cost and high accuracy, and therefore is more competitive in the market. Accordingly, the optical touch monitor has become one of the most popular large-scale touch monitors.
The optical touch monitor adopts a plurality of optical lenses disposed around the edge of the screen for capturing the image of the finger of the user operating the monitor, and analyzing the position of the shadow in the captured image caused by the finger shielding the light, so as to obtain a relative angle of the touch point of the finger to the optical lens. Finally, the optical touch monitor calculates the precise position of the touch points according to the known distance between the optical lenses by using the triangulation method.
In the application of the single-touch detection, the above-mentioned method for recognizing the position of the finger according to the shadow of the finger has reached fairly high accuracy. However, in the application of multi-touch detection, since the fingers is very close, at certain angles, the positions of different fingers in the image captured by the optical lenses may be overlapped, or even shielded by another finger, which leads to the optical touch monitor wrongly determining the operation as single-touch operation.
For example, FIG. 1 is a schematic view of a conventional optical touch monitor detecting a touch of a finger. Referring to FIG. 1, in the conventional optical touch monitor 10, the optical lenses 12 and 13 are respectively disposed at corners of the same side, for example, an upper left corner and an upper right corner, of the screen 11, and the optical lenses 12 and 13 face toward another side of the screen 11 to capture the gesture of the user operating the screen 11. Herein, when the user uses two fingers 14 and 15 to touch the screen 11, because the position of the finger 14 is located right between the optical lens 12 and the finger 15, the finger 15 is shielded. Accordingly the optical touch monitor 10 can only recognize the image of the finger 14 instead of the image of the finger 15 from the images captured by the optical lens 12, which subsequently causes the position of the finger 15 detected by the optical touch monitor 10 to be shifted, and accordingly affects the accuracy of the multi-touch recognition of the optical touch monitor.